When using the Desktop Plane plugin and switching viewports the top-most window in the new viewport should be focused, right now the focus does not change and you end up with the focused window being off screen

I looked at the rotate cube plugin which does not have this bug and came up with this patch which appears to work

diff --git a/plugins/plane.c b/plugins/plane.c
index 0ebfa2e..4581177 100644
--- a/plugins/plane.c
+++ b/plugins/plane.c
@@ -188,7 +188,7 @@ planePreparePaintScreen (CompScreen *s,
     PLANE_SCREEN (s);
 
     ps->timer -= msSinceLastPaint;
-
+    focusDefaultWindow (s->display);
     UNWRAP (ps, s, preparePaintScreen);
 
     (* s->preparePaintScreen) (s, msSinceLastPaint);